Introduction:

During our stay at Moolooloo Station we got to interview the Station Manager Mark Clifford. One of the questions we asked him was how important it was to protect the land from overgrazing or soil erosion from the presence of cattle. This was his answer:

“Well it’s critical and is a fairly large part of our job. As a company we use things like satellite imagery. There’s a Northern Territory range management body that actually comes out here and monitors certain sites on an annual basis to make sure there’s no pasture degradation (nonproductive). Obviously we also keep a close eye on the paddocks. There’s a scientist within the company who does a lot of work looking after the pastures. “

The reason cattle ranching in the Victoria River basin has been so successful since Nat Buchanan first stocked nearby station Victoria River Downs in 1884 is largely because of the protein rich grasses that thrive on the black clay soil and the amount of rainfall the area receives each year (around 28-30 inches per annum). But, during drought years, when reduced vegetation in turn means the soil is more open to erosion from the wind, the land is in serious danger of becoming unproductive. Should a particularly dry winter (April through October) be followed directly by a particularly wet summer (November through March), the topsoil will be further eroded by floodwater. Add cattle to the equation, especially more[than the pasture can hold], and you could be in trouble. Mark continues:

“It’s not impossible to have a drought year, in which instance we have to look quite closely at our cow/calf unit per square kilometre – normally around 6 to 1 on Moolooloo. In drought years we’d have to look at reducing this figure to maybe 3 or 4, or even less, and taking the surplus animals off the land.”

It seems that monitoring the pastures, either by satellite imagery from space or by a scientist on the ground, is the method that Mark uses to safeguard his pastures. Data from monitoring procedures can be used in conjunction with computers to build ‘models’ from which he can make range management decisions, before it gets too late and erosion sets in.

Vocabulary:

• drought
• vegetation
• surplus
• erosion

Materials:

• Guidebook to rangeland grasses and vegetation
• Landsat photos for comparison of land use over time
• Journals to record data and observations

Preparation:

• Study a variety of photos showing ‘before and after’ pictures of reclaimed pasture land. (A local agriculture office could provide resource materials)
• Research native grasses in your area. Make a list of those grasses.
• List the species that have been introduced from other areas of the country.

Procedure:

• Investigate the climate in your area. Make a bar graph showing rainfall for each month of the year.
• Determine the most common types of native vegetation and gather samples. Identify those grasses which are most commonly found in local pastures.
• Identify the weeds that are most common. Determine if they are native or are introduced species.
• Collect and dry samples of the vegetation, then classify and categorize the samples into two categories of native plants and introduced species.
• Record observations in student journals.
• Have a local range management expert speak to the class about the effects of drought and excessive moisture on vegetation.
  

Analyze and conclude:

• Identify grasses that thrive in the particular climate in which they live. Recognize that certain grasses will be more productive in proportion to the amount of rainfall that the region receives each year.
• Research introduced species, such as Kentucky Bluegrass, in a semi arid environment. Discover that more water is needed to insure that the grass survives.
• Make a graph or a chart listing the types of grasses in your area. Compare and contrast the native grass with the yearly rainfall. Compare and contrast the introduced species with the extra water that is needed to supplement yearly rainfall.
• In journals, record observations as to the effects on the environment that introduced species can produce. Be sure to include the extra water usage that may be needed to keep introduced species of grass alive in non native environments.

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